Developable bottom antireflective coating composition and pattern forming method using thereof

ABSTRACT

The present invention relates to a developable bottom antireflective coating (BARC) composition and a pattern forming method using the BARC composition. The BARC composition includes a first polymer having a first carboxylic acid moiety, a hydroxy-containing alicyclic moiety, and a first chromophore moiety; a second polymer having a second carboxylic acid moiety, a hydroxy-containing acyclic moiety, and a second chromophore moiety; a crosslinking agent; and a radiation sensitive acid generator. The first and second chromophore moieties each absorb light at a wavelength from 100 nm to 400 nm. In the patterning forming method, a photoresist layer is formed over a BARC layer of the BARC composition. After exposure, unexposed regions of the photoresist layer and the BARC layer are selectively removed by a developer to form a patterned structure in the photoresist layer. The BARC composition and the pattern forming method are especially useful for implanting levels.

FIELD OF THE INVENTION

This invention relates generally to antireflective coating (ARC)compositions, and more particularly to developable bottom antireflectivecoating (DBARC) compositions for using with an overlying photoresist.This invention is also directed to pattern forming methods of using suchDBARC compositions.

BACKGROUND OF THE INVENTION

Photolithography is a process widely used in semiconductor industry tofabricate electronic devices which uses light to transfer a geometricpattern from a photomask to a substrate such as a silicon wafer. In aphotolithography process, a photoresist layer is first formed on thesubstrate. The photoresist is exposed through a photomask with a desiredpattern to a source of actinic radiation. The exposure causes a chemicalreaction in the exposed areas of the photoresist and creates a latentimage corresponding to the mask pattern in the photoresist layer. Thephotoresist is next developed in a developer, usually an aqueous basesolution, to form a pattern in the photoresist layer. The patternedphotoresist can then be used as a mask for subsequent fabricationprocesses on the substrate, such as deposition, etching, or ionimplantation processes.

Two types of photoresist have been used in photolithography: positiveresist and negative resist. A positive resist is initially insoluble inthe developer. After exposure, the exposed region of the resist becomessoluble in the developer and is then selectively removed by thedeveloper during the subsequent development step. A negative resist, onthe other hand, is initially soluble in the developer. Exposure toradiation causes the exposed region of the resist to become insoluble inthe developer. During the subsequent development step, the unexposedregion of the negative resist is selectively removed by the developer,leaving the exposed region on the substrate to form a pattern.

In a photolithography process, exposure of the photoresist layer to theactivation radiation is an important step in attaining a high resolutionphotoresist image. However, reflection of the activation radiation fromthe photoresist and the underlying substrate substantially limits theresolution of the process. Two major problems of the reflected radiationare: (1) thin film interference effects or standing waves, which arecaused by variations in the total light intensity in the photoresistfilm as the photoresist thickness changes; and (2) reflective notching,which occurs when the photoresist is patterned over substratescontaining topographical features.

The reflected radiation from the photoresist and the underlyingsubstrate has become increasingly detrimental to the lithographicperformance of the photoresist under high numerical aperture (NA) andshort wavelength (such as 248 nm, 193 nm, and shorter wavelengths)exposure conditions. In implanting levels, the detrimental effect of thereflected radiation is even more pronounced due to the existence ofsurface topography generated after gate patterning and/or use of variousreflective substrates, such as silicon, silicon nitride and siliconoxide, for advanced semiconductor devices.

Both top antireflective coatings (TARCs) and bottom antireflectivecoatings (BARCs) have been used in the industry to control the reflectedradiation and to improve the lithographic image of the photoresist. Thereflectivity control provided by a TARC layer is in general not as goodas that obtained with a BARC layer. Using a BARC layer, however,generally requires an etch step to remove the BARC layer in order totransfer the resist pattern into the substrate. The etch step couldcause resist thinning, wreck damages to the substrate, and affect theperformance of the final device. The additional etch step to remove theBARC layer also increases cost and operational complexity inphotolithography.

Recently, DBARC materials have been used to alleviate the reflectivitycontrol issues with some success. DBARC materials are removable by thedeveloper in the development step, eliminating the need of theadditional etch step. However, most known DBARC materials in the art arecompatible only with positive photoresists. The DBARC materials forpositive photoresists become soluble to the developer upon radiation inthe same manner as the positive photoresists.

Many implanting levels in semiconductor manufacturing employ negativephotoresists because negative photoresists provide superior lithographicperformance over topography and have less resist shrinkage during ionimplantation compared with positive photoresists. Thus, there remains aneed for a BARC composition that is developable in a developer,compatible with the overlying negative photoresist, and has desiredoptical properties so that it can be used as a BARC suitable especiallyfor implanting levels.

SUMMARY OF THE INVENTION

The present invention provides a wet developable BARC composition. Thisinvention also provides a pattern forming method using the BARCcomposition.

In one aspect, this invention provides a BARC composition whichincludes: a first polymer comprising a first carboxylic acid moiety, ahydroxy-containing alicyclic moiety, and a first chromophore moietywhich absorbs light at a wavelength selected from a range from 100 nm to400 nm; a second polymer comprising a second carboxylic acid moiety, ahydroxy-containing acyclic moiety, and a second chromophore moiety whichabsorbs light at a wavelength selected from a range from 100 nm to 400nm; a crosslinking agent; and a radiation sensitive acid generator.

In another aspect, the present invention relates to a method of forminga patterned material structure on a substrate. The method includes thesteps of: providing a substrate with a layer of the material; applying aBARC composition to the substrate to form a BARC layer over the materiallayer, the BARC composition comprising: a first polymer comprising afirst carboxylic acid moiety, a hydroxy-containing alicyclic moiety, anda first chromophore moiety which absorbs light at a wavelength selectedfrom a range from 100 nm to 400 nm; a second polymer comprising a secondcarboxylic acid moiety, a hydroxy-containing acyclic moiety, and asecond chromophore moiety which absorbs light at a wavelength selectedfrom a range from 100 nm to 400 nm; a crosslinking agent; and aradiation sensitive acid generator; forming a photoresist layer over theBARC layer; patternwise exposing the photoresist layer to radiation; anddeveloping the substrate with a developer, whereby unexposed portions ofthe photoresist layer and the BARC layer are selectively removed by thedeveloper to form a patterned structure in the photoresist layer.

The photoresist layer in the above method is preferably a negativephotoresist.

The developer in the above method is preferably an aqueous alkalinedeveloper.

The above method may further include a step of: transferring thepatterned structure to the material layer. Preferably, the patternedstructure is transferred by ion implantation to form a pattern of ionimplanted material in the material layer.

The first carboxylic acid moiety and the second carboxylic acid moietyin the BARC composition are each independently selected from the groupconsisting of an acrylic acid monomer unit, a methacrylic acid monomerunit, a 4-vinylbenzoic acid monomer unit, a 2-carboxyethyl acrylatemonomer unit, a 2-carboxyethyl methacrylate monomer unit, amono-2-(methacryloyloxy)ethyl succinate monomer unit, and amono-2-(acryloyloxy)ethyl succinate monomer unit.

The hydroxy-containing alicyclic moiety of the BARC compositionpreferably includes an adamantyl group. More preferably, thehydroxy-containing alicyclic moiety is a monomer unit derived from amonomer selected from the group consisting of the following structures:

wherein p represents a positive integer from 1 to 30.

The hydroxy-containing acyclic moiety of the BARC composition ispreferably a monomer unit derived from a monomer selected from the groupconsisting of the following structures:

wherein s represents a positive integer from 1 to 30; R is a saturatedcarbon chain having a total number of carbon atoms from 1 to 30.

The first chromophore moiety and the second chromophore moiety of theBARC composition preferably each include an aromatic group. Morepreferably, the first chromophore moiety and the second chromophoremoiety each independently is a monomer unit derived from a monomerselected from the group consisting of the following structures:

wherein m represents a positive integer from 1 to 30; n represents aninteger from 0 to 30.

The crosslinking agent of the BARC composition is preferably aglycoluril compound.

The radiation sensitive acid generator of the BARC compositionpreferably includes at least one of an onium salt, a succinimidederivative, a diazo compound, and a nitrobenzyl compound.

The BARC composition may further includes at least one of a solvent, aquencher, and a surfactant. The solvent may be at least one of an ether,an alcohol, a glycol ether, an aromatic hydrocarbon, a ketone, and anester. Preferably, the BARC composition includes: about 0.1 to about 29wt. % of the first polymer; about 0.1 to about 29 wt. % of the secondpolymer; about 0.1 to about 30 wt. % of the crosslinking agent, based onthe total weight of the first and second polymers; about 0.1 to about 30wt. % of the radiation sensitive acid generator, based on the totalweight of the first and second polymers; and about 70 to about 99.9 wt.% of the solvent. Preferably, the weight percentage of the first polymeris higher than the weight percentage of the second polymer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The terms “a” and “an” herein do not denote a limitation of quantity,but rather denote the presence of at least one of the referenced item.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and the description includesinstances where the subsequently described event or circumstance occursand instances where it does not.

When an element, such as a layer, is referred to as being “on” or “over”another element, it can be directly on the other element or interveningelements may also be present. In contrast, when an element is referredto as being “directly on” or “directly over” another element, there areno intervening elements present.

As stated above, the present invention is directed to a BARC compositionfor applying between a substrate and a photoresist layer to reduce oreliminate reflected radiation. The BARC composition is developable in adeveloper. A preferred example of the developer is an aqueous alkalinedeveloper. More preferably, the developer is a tetramethyl ammoniumhydroxide (TMAH) aqueous developer. The BARC composition is preferablynegative working, i.e., unexposed portions of a BARC layer formed fromthe BARC composition are selectively removed by the developer in thedevelopment step while exposed portions of the BARC layer stay. Thus,the BARC composition of the present invention is compatible withnegative photoresists and is suitable for lithographic levels wherenegative photoresists are used, such as implanting levels.

In one embodiment, the BARC composition includes a first polymercomprising a first carboxylic acid moiety, a hydroxy-containingalicyclic moiety, and a first chromophore moiety which absorbs light ata wavelength selected from a range from 100 nm to 400 nm; a secondpolymer comprising a second carboxylic acid moiety, a hydroxy-containingacyclic moiety, and a second chromophore moiety which absorbs light at awavelength selected from a range from 100 nm to 400 nm; a crosslinkingagent; and a radiation sensitive acid generator.

In the BARC composition, the first carboxylic acid moiety and the secondcarboxylic acid moiety provide developer solubility in an aqueousalkaline developer. The first carboxylic acid moiety and the secondcarboxylic acid moiety may have the same structure or differentstructures. An example of the first and second carboxylic acid moietiesis a monomer unit of a polymer which contains a carboxylic acid group.The monomer unit may contain more than one carboxylic acid group.Examples of monomers from which the first carboxylic acid moiety and thesecond carboxylic acid moiety may derive include, but are not limitedto: acrylic acid (1), a methacrylic (2), 4-vinylbenzoic acid (3),2-carboxyethyl acrylate (4), 2-carboxyethyl methacrylate (5),mono-2-(methacryloyloxy)ethyl succinate (6), andmono-2-(acryloyloxy)ethyl succinate (7).

The hydroxy-containing alicyclic moiety of the first polymer in the BARCcomposition may be derived from a monomer containing both a hydroxygroup and an alicyclic group. The hydroxy group may be connecteddirectly to the alicyclic group. Alternatively, there may be anintervening group between the hydroxy and alicyclic groups. Examples ofsuch an intervening group include an alkyl group and an alkoxy group.The hydroxy-containing alicyclic moiety may contain more than onehydroxy group.

The alicyclic group of the hydroxy-containing alicyclic moiety may be amonocyclic group or a polycyclic group. Preferably, the alicyclic groupis a polycyclic group such as an adamantyl group. Examples of monomersfrom which the hydroxy-containing alicyclic moiety may derive include,but are not limited to: 3-hydroxy-1-adamantylmethacrylate (8),3-(2′-hydroxyethoxy)-1-adamantylmethacrylate (9),3-hydroxy-1-adamantylacrylate (10),3-(2′-hydroxyethoxy)-1-adamantylacrylate (11), and other monomers withchemical structures (12) and (13).

wherein the symbol p represents a positive integer having a value from 1to 30 except 2.

The hydroxy-containing acyclic moiety of the second polymer in the BARCcomposition preferably does not contain any cyclic structure.Preferably, the hydroxy-containing acyclic moiety is ahydroxyalkylmethacrylate monomer unit or a hydroxyalkylacrylate monomerunit. Examples of monomers from which the hydroxy-containing acyclicmoiety may derive include, but are not limited to:2-hydroxyethylmethacrylate (14), 2-hydroxyethylacrylate (15), and othermonomers with chemical structures (16)-(19).

wherein the symbol s represents a positive integer having a value from 1to 30 except 2; the symbol R represents a saturated carbon chain havinga total number of carbon atoms from 1 to 30.

The first chromophore moiety and the second chromophore moiety arenecessary to provide sufficient absorption coefficient k for the BARCcomposition. Typical target values for the absorption coefficient k ofthe BARC composition are from 0.01 to 2.0 at the wavelength of radiationfor the overlying photoresist layer. More preferably, the absorptioncoefficient k of the BARC composition is from 0.01 to 1.0 at thewavelength of radiation for the overlying photoresist layer.

The choice for the first chromophore moiety and the second chromophoremoiety depends on the exposure wavelength for the overlying photoresistlayer. For exposure wavelengths of 248 nm and 193 nm, the firstchromophore moiety and the second chromophore moiety preferably eachincludes an aromatic group. The first chromophore moiety and the secondchromophore moiety may have the same structure or different structures.Examples of monomers from which the first chromophore moiety and thesecond chromophore moiety may derive include, but are not limited to:9-anthrylmethylmethacrylate (20), 9-anthrylmethylacrylate (21),4-hydroxy styrene (22), styrene (23), and other monomers with thefollowing chemical structures (24)-(52):

wherein the symbol m represents a positive integer from 1 to 30; thesymbol n represents an integer from 0 to 30.

The first polymer of the BARC composition may contain from 20 mol % to70 mol % of the first carboxylic acid moiety, from 20 mol % to 70 mol %of the hydroxy-containing alicyclic moiety, and from 5 mol % to 50 mol %of the first chromophore moiety. The second polymer of the BARCcomposition may contain from 20 mol % to 70 mol % of the secondcarboxylic acid moiety, from 20 mol % to 70 mol % of thehydroxy-containing acyclic moiety, and from 5 mol % to 50 mol % of thesecond chromophore moiety.

The BARC composition also includes a crosslinking agent. In the exposedregions, the crosslinking agent can react with the hydroxy groups of thefirst and second polymers in a manner which is catalyzed by acid and/orby heating to interlink or crosslink the polymer chains. Thecrosslinking of the polymer chains reduces the solubility of the exposedregions in the developer and creates the solubility difference in thedeveloper between the exposed and unexposed regions of the BARC layer.

Generally, the crosslinking agent of the BARC composition of the presentinvention is any suitable crosslinking agent known in the negativephotoresist art which is compatible with the other selected componentsof the BARC composition. The crosslinking agent typically acts tocrosslink the first and second polymers in the presence of a generatedacid. Typical crosslinking agents are glycoluril compounds such astetramethoxymethyl glycoluril, methylpropyltetramethoxymethylglycoluril, and methylphenyltetramethoxymethyl glycoluril, availableunder the POWDERLINK® trademark from Cytec Industries. Other possiblecrosslinking agents include: 2,6-bis(hydroxymethyl)-p-cresol compoundssuch as those disclosed in Japanese Laid-Open Patent Application (Kokai)No. 1-293339, etherified amino resins, for example, methylated orbutylated melamine resins (N-methoxymethyl- or N-butoxymethyl-melaminerespectively), and methylated/butylated glycolurils, for example asdisclosed in Canadian Patent No. 1 204 547. Other crosslinking agentssuch as bis-epoxies or bis-phenols (e.g., bisphenol-A) may also be used.Combinations of two or more crosslinking agents may be preferred in someembodiments.

Some particular examples of crosslinking agents suitable for use in theBARC composition according to the present invention include, but are notlimited to:

The BARC composition of the present invention also includes a radiationsensitive acid generator. The radiation sensitive acid generator, alsoknown as photoacid generator (PAG), is a compound that generates an acidupon exposure to radiation. The PAG of the present invention may be oneof an onium salt, a succinimide derivative, a diazo compound, anitrobenzyl compound, and the like. To minimize acid diffusion for highresolution capability, the PAGs may be such that they generate bulkyacids upon exposure to radiation. Such bulky acids may include at least4 carbon atoms.

A preferred PAG that may be employed in the present invention is anonium salt, such as an iodonium salt or a sulfonium salt, and/or asuccinimide derivative. In various exemplary embodiments of the presentinvention, the preferred PAG may include4-(1-butoxynaphthyl)tetrahydrothiophenium perfluorobutanesulfonate,triphenyl sulfonium perfluorobutanesulfonate, t-butylphenyl diphenylsulfonium perfluorobutanesulfonate,4-(1-butoxynaphthyl)tetrahydrothiophenium perfluorooctanesulfonate,triphenyl sulfonium perfluorooctanesulfonate, t-butylphenyl diphenylsulfonium perfluorooctanesulfonate, di(t-butylphenyl) iodoniumperfluorobutane sulfonate, di(t-butylphenyl) iodonium perfluorohexanesulfonate, di(t-butylphenyl) iodonium perfluoroethylcyclohexanesulfonate, di(t-buylphenyl)iodonium camphoresulfonate, andperfluorobutylsulfonyloxybicylo[2.2.1]-hept-5-ene-2,3-dicarboximide. Anyof these PAGs may be used singly or in a mixture of two or more. Bothfluorinated and fluorine-free PAGs can be used in the present invention.

The specific PAG selected will depend on the radiation being used forpatterning the overlying photoresist layer. PAGs are currently availablefor a variety of different wavelengths of light from the visible rangeto the extreme UV range. Preferably, the PAG is one suitable for use in248 nm (KrF) and 193 nm (ArF) lithography.

The BARC composition of the present invention may further include asolvent, and other performance enhancing additives, for example, aquencher and a surfactant. The solvent is used to dissolve the first andsecond polymers and other components of the BARC composition. Examplesof suitable solvents include, but are not limited to: ethers, glycolethers, alcohol, aromatic hydrocarbons, ketones, esters and the like.Suitable glycol ethers include: 2-methoxyethyl ether (diglyme), ethyleneglycol monomethyl ether, propylene glycol monomethyl ether (PGME),propylene glycol monomethylether acetate (PGMEA), propylene glycolmonoethyl ether (PGEE) and the like. Suitable alcohols include:3-methoxy-1-butanol, and 1-methoxy-2-butanol. Suitable aromatichydrocarbon solvents include: toluene, xylene, and benzene. Examples ofketones include: methylisobutylketone, 2-heptanone, cycloheptanone,gamma-butyrolactone (GBL), and cyclohexanone. An example of an ethersolvent is tetrahydrofuran, whereas ethyl lactate and ethoxy ethylpropionate are examples of ester solvents that may be employed in thepresent invention. A solvent system including a mixture of theaforementioned solvents is also contemplated. Examples of mixed solventsmay include PGMEA and GBL, with the wt. % of one solvent in the totalweight of the solvent mixture from about 1 to about 99 wt. %.

The quencher that may be used in the BARC composition of the presentinvention may comprise a weak base that scavenges trace acids, while nothaving an excessive impact on the performance of the BARC. Illustrativeexamples of quenchers that can be employed in the present inventioninclude, but are not limited to: aliphatic amines, aromatic amines,carboxylates, hydroxides, or combinations thereof and the like.

The optional surfactants that can be employed in the BARC compositionsinclude any surfactant that is capable of improving the coatinghomogeneity of the BARC composition of the present invention.Illustrative examples include: fluorine-containing surfactants such as3M's FC-4430® and siloxane-containing surfactants such as UnionCarbide's Silwet® series.

The weight percentage of the first polymer in the BARC composition ispreferably higher than the weight percentage of the second polymer. Invarious exemplary embodiments of the present invention, the BARCcomposition may include: about 0.1 to about 29 wt. % of the firstpolymer, more preferably about 0.2 to about 15 wt. %; about 0.1 to about29 wt. % of the second polymer, more preferably about 0.2 to about 15wt. %; about 0.1 to about 30 wt. % of the crosslinking agent, based onthe total weight of the first and second polymers, more preferably about0.5 to about 10 wt. %; about 0.1 to about 30 wt. % of the radiationsensitive acid generator, based on the total weight of the first andsecond polymers, more preferably about 0.5 to about 10 wt. %; and about70 to about 99.9 wt. % of the solvent, more preferably about 90 to about99.9 wt. %.

In various exemplary embodiments, the BARC composition may furthercomprise a quencher, which may typically be present in amounts of about0.01 to about 10.0 wt. % based on the total weight of the first andsecond polymers, and a surfactant, which may typically be present inamounts of about 0.001 to about 1.0 wt. %, based on the total weight ofthe first and second polymers.

Note that the amounts given above are exemplary and that other amountsof each of the above components, which are typically employed in thephotolithography industry, can also be employed herein.

The present invention also encompasses a method of using the BARCcomposition described above to form patterned material features on asubstrate. In one embodiment, such a method includes the steps of:providing a substrate with a layer of the material; applying a BARCcomposition to the substrate to form a BARC layer over the materiallayer, the BARC composition comprising: a first polymer comprising afirst carboxylic acid moiety, a hydroxy-containing alicyclic moiety, anda first chromophore moiety which absorbs light at a wavelength selectedfrom a range from 100 nm to 400 nm; a second polymer comprising a secondcarboxylic acid moiety, a hydroxy-containing acyclic moiety, and asecond chromophore moiety which absorbs light at a wavelength selectedfrom a range from 100 nm to 400 nm; a crosslinking agent; and aradiation sensitive acid generator; forming a photoresist layer over theBARC layer; patternwise exposing the photoresist layer to radiation; anddeveloping the substrate with a developer, whereby unexposed portions ofthe photoresist layer and the BARC layer are selectively removed by thedeveloper to form a patterned structure in the photoresist layer.

The substrate is suitably any substrate conventionally used in processesinvolving photoresists. For example, the substrate can be silicon,silicon oxide, aluminum-aluminum oxide, gallium arsenide, ceramic,quartz, copper or any combination thereof, including multilayers. Thesubstrate can include one or more semiconductor layers or structures andcan include active or operable portions of semiconductor devices.

The material layer may be a metal conductor layer, a ceramic insulatorlayer, a semiconductor layer or other material depending on the stage ofthe manufacture process and the desired material set for the endproduct. The BARC compositions of the invention are especially usefulfor lithographic processes used in the manufacture of integratedcircuits on semiconductor substrates. The BARC compositions of theinvention can be used in lithographic processes to create patternedmaterial layer structures such as metal wiring lines, holes for contactsor vias, insulation sections (e.g., damascene trenches or shallow trenchisolation), trenches for capacitor structures, ion implantedsemiconductor structures for transistors, etc. as might be used inintegrated circuit devices.

The BARC layer may be formed by virtually any standard means includingspin coating. The BARC layer may be baked to remove any solvent from theBARC and improve the coherence of the BARC layer. The preferred range ofthe baking temperature for the BARC layer is from about 70° C. to about150° C., more preferably from about 90° C. to about 130° C. Thepreferred range of thickness of the BARC layer is from about 5 nm toabout 150 nm, more preferably from about 10 nm to about 100 nm.

The BARC layer is preferably insoluble in a typical resist solvent suchas propylene glycol monomethylether acetate (PGMEA) after coating andbaking The insolubility makes it possible to apply a photoresist layerover the BARC layer without intermixing these two layers.

A photoresist layer is then formed over the BARC layer. The photoresistlayer is preferably a negative photoresist such as NSD2803Y andKEFK3034, which are commercially available from JSR Corporation. Thephotoresist layer may be formed by virtually any standard meansincluding spin coating. The photoresist layer may be baked (postapplying bake (PAB)) to remove any solvent from the photoresist andimprove the coherence of the photoresist layer. The preferred range ofthe PAB temperature for the photoresist layer is from about 70° C. toabout 150° C., more preferably from about 90° C. to about 130° C. Thepreferred range of thickness of the photoresist layer is from about 20nm to about 400 nm, more preferably from about 30 nm to about 300 nm.

In some cases, a top antireflective coating layer may be applied overthe photoresist layer to further reduce or eliminate reflectedradiation.

The photoresist layer is then patternwise exposed to the desiredradiation. The radiation employed in the present invention can bevisible light, ultraviolet (UV), extreme ultraviolet (EUV) and electronbeam (E-beam). It is preferred that the imaging wavelength of theradiation is about 248 nm, 193 nm or 13 nm. It is more preferred thatthe imaging wavelength of the radiation is about 248 nm. The patternwiseexposure is conducted through a mask which is placed over thephotoresist layer.

After the desired patternwise exposure, the photoresist layer istypically baked (post exposure bake (PEB)) to further complete theacid-catalyzed reaction and to enhance the contrast of the exposedpattern. The preferred range of the PEB temperature is from about 70° C.to about 150° C., more preferably from about 90° C. to about 130° C. Insome instances, it is possible to avoid the PEB step since for certainchemistries, such as acetal and ketal chemistries, deprotection of theresist polymer proceeds at room temperature. The post-exposure bake ispreferably conducted for about 30 seconds to 5 minutes.

After PEB, if any, the photoresist layer with the desired pattern isobtained (developed) by contacting the photoresist layer with adeveloper. A preferred example of the developer is an aqueous alkalinedeveloper. More preferably, the developer is a tetramethyl ammoniumhydroxide (TMAH) aqueous developer. An example of the TMAH aqueousdeveloper is 0.26 N TMAH developer. The developer selectively dissolvesunexposed portions of the photoresist layer and the BARC layer to form apatterned structure in the photoresist layer. Hence, the developmentstep in the present invention is a “negative development” step. The wetremoval of the unexposed portions of the BARC layer eliminate the needof an additional etch step.

The pattern from the photoresist layer may then be transferred to theexposed portions of underlying material layer of the substrate usingtechniques known in the art. Preferably, the pattern is transferred byion implantation to form a pattern of ion implanted material.Alternatively, the transfer may be done by etch methods such as reactiveion etching or wet etching. Once the desired pattern transfer has takenplace, any remaining photoresist layer and/or BARC layer may be removedusing conventional stripping techniques.

Examples of general lithographic processes where the composition of theinvention may be useful are disclosed in U.S. Pat. Nos. 4,855,017;5,362,663; 5,429,710; 5,562,801; 5,618,751; 5,744,376; 5,801,094;5,821,469 and 5,948,570. Other examples of pattern transfer processesare described in Chapters 12 and 13 of “Semiconductor Lithography,Principles, Practices, and Materials” by Wayne Moreau, Plenum Press,(1988). It should be understood that the invention is not limited to anyspecific lithography technique or device structure.

The invention is further described by the examples below. The inventionis not limited to the specific details of the examples.

EXAMPLE 1 Synthesis of MAA/HADMA/ANTMA (P1)

To a mixture of methacrylic acid (0.775 g, 9 mmol), 3-hydroxy-1adamantylmethacrylate (1.42 g, 6 mmol), 9-anthrylmethylmethacrylate(1.38 g, 5 mmol) in 20 mL of tetrahydrofuran (THF) was added2,2′-azobis(2-methylpropionitrile (0.24 g, 1.5 mmol). The resultingsolution was purged by nitrogen for 30 minutes before it was heats to72° C. for 18 hours under nitrogen. The solution was then cooled to roomtemperature and added drop-wise into 400 mL of de-ionized water. Thesolid was filtered with a frit funnel, washed with water (2×200 ml) anddried in a vacuum oven at 50° C. for 24 hours to afford 3.1 gram of P1as white solid.

EXAMPLE 2 Synthesis of MAA/HEMA/ANTMA (P2)

To a mixture of methacrylic acid (0.775 g, 9 mmol),2-hydroxyethylmethacrylate (0.78 g, 6 mmol), 9-anthrylmethylmethacrylate(1.38 g, 5 mmol) in 20 mL of THF was added2,2′-azobis(2-methylpropionitrile (0.24 g, 1.5 mmol). The resultingsolution was purged by nitrogen for 30 minutes before it was heats to72° C. for 18 hours under nitrogen. The solution was then cooled to roomtemperature and added drop-wise into 400 mL of de-ionized water. Thesolid was filtered with a frit funnel, washed with water (2×200 ml) anddried in a vacuum oven at 50° C. for 24 hours to afford 2.5 gram of P2as white solid.

EXAMPLE 3 Synthesis of MAA/HEADMA/ANTMA (P3)

To a mixture of methacrylic acid (0.775 g, 9 mmol),3-(2′-hydroxyethoxy)-1-adamantylmethacrylate (1.68 g, 6 mmol),9-anthrylmethylmethacrylate (1.38 g, 5 mmol) in 20 mL of THF was added2,2′-azobis(2-methylpropionitrile (0.24 g, 1.5 mmol). The resultingsolution was purged by nitrogen for 30 minutes before it was heats to72° C. for 18 hours under nitrogen. The solution was then cooled to roomtemperature and added drop-wise into 400 mL of de-ionized water. Thesolid was filtered with a frit funnel, washed with water (2×200 ml) anddried in a vacuum oven at 50° C. for 24 hours to afford 3.5 gram of P3as white solid.

EXAMPLE4 Developable BARC formulation (F1)

1.0502 gram of the terpolymer (P1) solid consisting of 45 mole % (molarpercentage) of methacrylic acid, 30 mole % of 3-hydroxy-1adamantylmethacrylate and 25 mole % of 9-anthrylmethylmethacrylate,12.8573 gram of 3.5 wt % solution of the terpolymer (P2) consisting of45 mole % of methacrylic acid, 30 mole % of 2-hydroxyethylmethacrylateand 25 mole % of 9-anthrylmethylmethacrylate in 3-methoxy-1-butanol,0.0751 gram of triphenyl sulfonium trifluoromethanesulfonate, 1.0726gram of 1 wt % solution of 1-tert-butyloxycarbonyl-2-phenylbenzimidazolein propylene glycol methyl ether acetate (PGMEA), 3.0106 gram of 1 wt %of tetramethoxymethyl glycoluril in 3-methoxy-1-butanol, and 3.6729 gramof 1 wt % solution of a perfluoroalkyl surfactant in PGMEA weredissolved in 55.4119 gram of 3-methoxy-1-butanol to make a developableBARC solution (F1). The resulting developable BARC solution was filteredthrough a 0.2 μm PTFE filter disc.

EXAMPLE 5 Developable BARC formulation (F2)

1.0504 gram of the terpolymer (P3) solid consisting of 45 mole % ofmethacrylic acid, 30 mole % of3-(2′-hydroxyethoxy)-1-adamantylmethacrylate and 25 mole % of9-anthrylmethylmethacrylate, 12.8582 gram of 3.5 wt % solution of theterpolymer (P2) consisting of 45 mole % of methacrylic acid, 30 mole %of 2-hydroxyethylmethacrylate and 25 mole % of9-anthrylmethylmethacrylate in 3-methoxy-1-butanol, 0.075 gram oftriphenyl sulfonium trifluoromethanesulfonate, 1.0691 gram of 1 wt %solution of 1-tert-butyloxycarbonyl-2-phenylbenzimidazole in PGMEA,3.0001 gram of 1 wt % of tetramethoxymethyl glycoluril in3-methoxy-1-butanol, and 3.6720 gram of 1 wt % solution of aperfluoroalkyl surfactant in PGMEA were dissolved in 55.3893 gram of3-methoxy-1-butanol to make a developable BARC solution (F2). Theresulting developable BARC solution was filtered through a 0.2 μm PTFEfilter disc.

EXAMPLE 6 Lithography Evaluation

To evaluate the lithographic performance of the resulting developableBARC under 248 nm radiation, the filtered developable BARC formulationsF1 or F2 was spin-coated for 60 seconds on a 12 inch silicon wafer at aspin speed of 1500 rpm. The film was baked at 120° C. for 60 seconds toafford a film thickness of 60 nm. A 248 nm negative resist KEFK3034 fromJSR was spin-coated for 60 seconds onto such a developable BARC layer ata spin speed of 1500 rpm to afford a resist film with a thickness of 250nm, the resulting developable BARC/resist stack was baked at 90° C. andexposed to 248 nm radiation (ASML scanner). The exposure pattern was anarray of lines and spaces of various dimensions. The exposed wafer waspost-exposure baked at 110° C. for 60 seconds, followed by a 0.26 N TMAHdeveloper puddle for 30 seconds. The resulting patterns of thedevelopable BARC/negative resist stack were examined by a scanningelectron microscopy (SEM). Under such a lithography condition, aline/space (470 nm/210 nm) pattern and a line/space (265 nm/165 nm)pattern were obtained.

While the present invention has been particularly shown and describedwith respect to preferred embodiments, it will be understood by thoseskilled in the art that the foregoing and other changes in forms anddetails may be made without departing from the spirit and scope of theinvention. It is therefore intended that the present invention not belimited to the exact forms and details described and illustrated butfall within the scope of the appended claims.

What is claimed is:
 1. A bottom antireflective coating (BARC)composition comprising: a first polymer comprising a first carboxylicacid moiety, a hydroxy-containing alicyclic moiety, and a firstchromophore moiety which absorbs light at a wavelength selected from arange from 100 nm to 400 nm; a second polymer comprising a secondcarboxylic acid moiety, a hydroxy-containing acyclic moiety, and asecond chromophore moiety which absorbs light at a wavelength selectedfrom a range from 100 nm to 400 nm; a crosslinking agent joining thefirst polymer and the second polymer; and a radiation sensitive acidgenerator.
 2. The BARC composition of claim 1, wherein the firstcarboxylic acid moiety and the second carboxylic acid moiety are eachindependently selected from the group consisting of: an acrylic acidmonomer unit, a methacrylic acid monomer unit, a 4-vinylbenzoic acidmonomer unit, a 2-carboxyethyl acrylate monomer unit, a 2-carboxyethylmethacrylate monomer unit, a mono-2-(methacryloyloxy)ethyl succinatemonomer unit, and a mono-2-(acryloyloxy)ethyl succinate monomer unit. 3.The BARC composition of claim 1, wherein the hydroxy-containingalicyclic moiety includes an adamantyl group.
 4. The BARC composition ofclaim 3, wherein the hydroxy-containing alicyclic moiety is a monomerunit derived from a monomer selected from the group consisting of thefollowing structures:

wherein p represents a positive integer from 1 to
 30. 5. The BARCcomposition of claim 1, wherein the hydroxy-containing acyclic moiety isa monomer unit derived from a monomer selected from the group consistingof the following structures:

wherein s represents a positive integer from 1 to 30; R is a saturatedcarbon chain having a total number of carbon atoms from 1 to
 30. 6. TheBARC composition of claim 1, wherein the first chromophore moiety andthe second chromophore moiety each includes an aromatic group.
 7. TheBARC composition of claim 6, wherein the first chromophore moiety andthe second chromophore moiety each independently is a monomer unitderived from a monomer selected from the group consisting of thefollowing structures:

wherein m represents a positive integer from 1 to 30; n represents aninteger from 0 to
 30. 8. The BARC composition of claim 1, wherein thecrosslinking agent is a glycoluril compound.
 9. The BARC composition ofclaim 1, wherein the radiation sensitive acid generator comprises atleast one of an onium salt, a succinimide derivative, a diazo compound,and a nitrobenzyl compound.
 10. The BARC composition of claim 1, furthercomprising at least one of a solvent, a quencher, and a surfactant. 11.The BARC composition of claim 10, wherein the solvent comprises at leastone of an ether, an alcohol, a glycol ether, an aromatic hydrocarbon, aketone, and an ester.
 12. The BARC composition of claim 11, wherein theBARC composition comprises: about 0.1 to about 29 wt. % of the firstpolymer; about 0.1 to about 29 wt. % of the second polymer; about 0.1 toabout 30 wt. % of the crosslinking agent, based on the total weight ofthe first and second polymers; about 0.1 to about 30 wt. % of theradiation sensitive acid generator, based on the total weight of thefirst and second polymers; and about 70 to about 99.9 wt. % of thesolvent.
 13. The BARC composition of claim 12, wherein the weightpercentage of the first polymer is higher than the weight percentage ofthe second polymer.